Laser scanning microscopes (such as two-photon and confocal microscopes) are widely used for acquiring images of narrow sections of cells and tissues, in which molecules of interest are tagged with fluorescent molecules, so that the latter render the former visible through emission of light. By acquiring multiple images of such thin sections, three-dimensional images of the samples can be obtained. In experiments involving fluorescence tagging with multiple colors, such as in studies of protein co-localization or protein-protein interactions (studied through Fluorescence Resonance Energy Transfer—FRET—which involves at least two different tags), a fourth dimension becomes necessary, i.e., the spectral dimension (i.e., the wavelength of the emitted light).